The airline satisfaction study measures passenger satisfaction with North American airlines based on seven criteria in order of importance: costs and fees; in-flight services; boarding, deplaning and baggage; flight crew, aircraft; check-in; and reservations.

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Passengers don't even mind the costs and fees as much anymore: Satisfaction with costs and fees rose from 618 last year to 642 this year.

Alaska Airlines continued to rank first among North American legacy carriers, increasing its customers' satisfaction by 20 points to 737 points, followed by Delta Air Lines in second place (693 points) and American Airlines in third place (684 points).

The average rating for the legacy carriers was 683 points out of a possible 1,000. Air Canada came in fourth with 683 points, followed by United Airlines (658 points) and US Airways (656 points).

"Alaska Airlines has been a pretty perennial winner in the traditional carrier category," says Rick Garlick, J.D. Power's global travel and hospitality practice lead. "It's never easy to get to the top, and it's tough to stay there."

Garlick notes Alaska's efforts to provide customers with a "very positive" in-flight experience, including improvements in seat comfort, entertainment and in some cases, allowing passengers to exit the aircraft from two places. "They strive to get better, and it creates overall an halo effect about how people feel about the airline."

Customers much prefer the low-cost carriers over the legacy carriers, awarding them an average of 763 points out of a possible 1,000 points.

JetBlue Airways dominated the low-cost category, ranking first for the 10th consecutive year, with 789 points out of a possible 1,000 points. Southwest Airlines came in second place (778 points), followed by WestJet in third place (734 points).

Southwest Airlines Rapid Rewards program came in second place, earning 731 points. JetBlue Airline TrueBlue program came in third with 707 points. United's program came in fourth with 691 points, followed by Delta (686 points), American (685 points) and US Airways (642 points).

The loyalty/rewards survey measures customer satisfaction based on six factors, listed in order of importance: easing of redeeming points or miles; reward program terms; account maintenance or management; ease of earning points or miles; variety of benefits available; and customer service.

As for its Alaska Airlines' rewards program win, Garlick credits its partner airline network and the ease with which customers can qualify for elite status.

It's not clear what Delta's plan to count dollars-spent as part of its reward program will do for customer satisfaction -- or its fifth-place ranking. And there's no place to go but up for American and U.S. Airways, whose merger will eventually combine their bottom-ranked rewards programs.

Are people really happy with their airlines?

Compared with 2013, airline ticket prices rose 5% in the first four months of 2014. The total was $32.4 billion in 2014, compared to $30.9 billion during the first four months of 2013, according to Airlines Reporting Corporation data of tickets sold by U.S.-based travel agencies, released Tuesday.

Despite these improvements in customer satisfaction, airlines don't do so well when compared with other industries.

Comparing airlines' average 712-point satisfaction, hotels (777 points), rental cars (775 points) and even mortgage lenders (771 points) do better in customer satisfaction, according to J.D. Power surveys on the same 1,000 scale.

"You may not think your airline experience is fabulous, but this is the best it's been in quite a while," says Garlick.